Practice Problems 2

# Practice Problems 2 - Fundamentals of Micromachining BIOEN...

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Fundamentals of Micromachining Homework 2 BIOEN 6421, EL EN 5221 & 6221, ME EN 5960 & 6960 3/21/02 Practice Problems #2 1. You are using KOH etching to define a 200 μ m thru-hole in a 100 wafer. What should the dimensions on your mask be if you are using a: a) 400 μ m thick wafer b) 600 μ m wafer. What would be the dimensions of the thru-hole be if you used the mask intended for the 400 μ m thick wafer on the 600 μ m thick wafer? 2. You are using KOH to etch ports in a 400 μ m thick wafer. What minimum thickness of SiO 2 is needed to provide a mask for KOH etching. You are using 20% KOH at 60 ° C? If Si 3 N 4 etches at 1.5 Å/min using the same conditions, how thick would it need to be to serve as a mask? (Hint: Use Appendix C in your textbook) 3. If the shape drawn below was used as a mask for KOH etching, draw a top and side view of what the hole would look like if allowed to go until only 111 planes are exposed. Assume the 100 planes are parallel to this page. 4.
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